A typical prior art valve apparatus contains a magnetic armature which actuates a closing element. The magnetic armature is located in a guiding sleeve surrounded by a magnetic coil, and is capable of displacement therein. The magnetic armature is provided with a plastic coating to improve the gliding quality on the part of the surface which is in contact with the guiding sleeve.
In addition to improving the gliding quality of the moving part within the non-moving part, it is also necessary in such valve arrangements to attenuate the impact of the moving part on the non-moving part. Thereby, damage of these parts, which are normally made of relatively hard materials, can be avoided.
Therefore, when designing an apparatus with at least two parts capable of moving relative to each other, and which may have contact with each other as a result of their relative movement, it is necessary to avoid damage to these parts. For this purpose, prior art devices contain springy attenuating means, e.g., being made of rubber, being installed between the moving parts.
However, this type of prior art attenuating means requires a relatively large space in order to produce effective attenuation over a long period of life. In many installations though, and especially in newer valve installations, only a small amount of space is available.
To provide the large space required to install the aforementioned prior art attenuating means would also necessitate a lengthening of the stroke of the magnetic armature, as required for faultless functioning of the valve arrangement. In addition, to actuate such a valve arrangement, a large amount of magnetic force would be necessary. This could be achieved, for example, by means of a relatively large magnetic coil and a relatively strong actuating current. However, it is not desirable to enlarge the magnetic coil or to increase the power consumption.
It is therefore an object of the present invention to provide an apparatus, e.g., a valve arrangement, having at least two movable parts which may have contact with each other, with an attenuating means which not only avoids damage to the movable parts, but which also requires very little additional space.